On Sun, Jan 25, 2015 at 12:25 AM, Maverick Peppers <[email protected]>
wrote:
> // Start of program4 process
> var fs = require('fs');
>
> // Asyncronously read and send the buffer object of a file whose path
> // is set int 2nd argument of the process to the callback function.
> var buffer = 0;
> fs.readFile(process.argv[2], fileReadCallBack);
>
> while(buffer == 0) {}
>
>
Code is blocked here as instructions are executed sequentially.
fileReadCallback is never called as you never free the thread's execution.
> var numOfNewLines = buffer.toString().split('\n').length-1;
> console.log(numOfNewLines);
>
> // Our callback function for our asyncronous file reading
> function fileReadCallBack(err, data) { if(!err){ buffer = data; } }
>
> I'm using NodeSchool.io's workshop <http://nodeschool.io/#workshoppers>
> to learn Nodejs. I'm on problem 4, *Async File I/O *and the above code
> runs forever. If the file reading is asynchronous, I'm thinking *var
> buffer* should no longer be 0 and the while-loop will terminate and move
> on.
>
> I know the correct solution would place the logic inside of the callback
> function, but I'm curious as to why the code above doesn't work as expected.
>
> Thanks!
>
Try this:
> var buffer = 0;
>
> console.log('outside setTimeout');
>
> setTimeout(function () {
> console.log('inside setTimeout');
> buffer = 1;
> }, 10);
>
> console.log('before while');
>
> while(buffer == 0) {}
>
> console.log('after while');
>
>
Cheers,
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Adrien Risser,
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M. +33 6 59 60 32 58
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